Mechanism for making bifocal lenses



A. E. PAIGE. MECHANISM FOR MAKING BIFOCALLENSES. APPLICATION FILED JUNE5. 1915. RENEWED 05c. 12. .1919.

1,347,653 Patented July 27, 1920.

8 SHEETS-SHEET I.

FIG I.

A. E. PAIGE. MECHANISM FOR MAKING BIFOCAL LENSES. APPLICATION FILED JUNE5. 1915. RENEWED DEC. 12, 1919.

1,347,653 Patented July 27, 1920.

8 SHEETS-SHEET 2.

WITNESS INVENTOR:

- A. E. PAIGE. MECHANISM FOR MAKING BIFOCAL LENSES. APPUCATION FILEDJUNE 5. 1915. RENEWED 02c. 12,-1919.

Patented July 27, 19 20.

8 SHEETS-SHEET 3- A. E. PAIGE.

MECHANISM FOR MAKING BIFOCAL LENSES. APPLICATION FILED JUNES, 1915.RENEWED DEC. 12. 1919.

1,347,653. 7 Pa tented July 27, 1920.

8 SHEETS-SHEET 4.

' WITNES%P I I 1NvE if 4 A. E. PAIGE. MECHANISM FOR MAKING BIFOCALLENSES. APPLICATION FILED JUNE 5, 1915. RENEWED 02c. 12. I919.

8 sflEETS-sHEET 5.

INVENTOR:

Patented July 27, 1920.

A. E. PAIGE. MECHANISM FOR MAKING BIFOCAL LENSES.

APPLICATION FILED JUNE 5, I915- RENEWED DEC- 12,1919- 1,347,653.

Patented July 27, 1920.

8 SHEETS-SHEET 6.

ill

INVENTQR:

A. E. PAIGE.

MECHANISM FOR MAKING mom muses. APPLICATION FILED JUNE 5, 1915. RENEWEDDEC- 12,1919. 1,347,653 I Patented July 27, 1920.

8 SHEETSSHEET 7.

WITNESSES: INVENT? A. E. PAIGE.

MECHANISM FOR MAKING BIFOCAL LENSES.

APPLICATION FILED JUNE 5,1915. RENEWED 05c. 12,1919.

Patented July 27, 1920.

8 SHEETS-SHEET 8. 56

I N-V E NTO/FZ:

WITNESSES:

ARTHUR E. PAIGE, 0F PHILADELPHIA, PENNSYLVANIA.

MECHANISM FOR- MAKING BIFOCAL LENSES.

Specification of Letters Patent.

Patented July 27,1920.

Original application filed March 4, 1915, Serial No. 12,028. Divided andthis application filed June 5,

1915, Serial No. 32,259.

To all whom it may concern:

Be it known that I, ARTHUR E. PAIGE, a citizen of the United States,residing at Philadelphia, in the State of Pennsylvania, have invented acertain new and useful Improvement in Mechanism for Making BifocalLenses, whereof the following is a specification reference being had tothe accompanying drawings.

My invention relates to means for producing curvec surfaces, andparticularly such surfaces as adjoin each other and are respectivelyuniformly curved to the junction line between them, so as to sharplydefine the latter. As hereinafter described, such means are adapted tosurface one side of glass to contemporaneously form a pair of bifocallenses, the glass being held with the respective minor areas adjoiningeach other and between their respective major areas and concentricallyrotated in cooperative relation with abrading means common to the glasswhich forms both members of such a pair. Such abrading means includes alap having an annular abrading surface presenting only a transverse lineof contact to the glass and having one circumferential edge of saidannular surface presented tangentially to the junction line between themajor and minor lens areas, so that that edge of the abrading surfaceextends obliquely over said junction line from its point of contact withthe glass; whereby the glass is abraded in a direction transverse tosaid junction line, so as to sharply define the latter. 31s hereinafterdescribed such oblique relation is determined by having the axes ofrotation of the glass and of the lap neither parallel nor at rightangles, but in acutely oblique transverse relation, and, although thelap axis may be maintained in radial relation with the axis of rotationof the glass, and is preferably so maintained in abrading the minor lenssurfaces, because the line of contact between the lap and the glass thenintersects the center of rotation of the minor lens areas; the axis ofrotation of the laps may extend tangentially to a circle described byrotation of any point on the surface of the glass, and is preferablythus maintained in abrading the major lens surfaces; because the path ofthe abrading material moved by the lap is then in a direction transverseto the path of the abrading material moved by the glass, thus impart-Renewed December 12, 1919. Serial No. 344,465.

ing a compound decussative motion to said material and preventing itfrom forming concentric ruts or scratches in the glass. Moreover, bypresenting the line of contact of the lap with the glass in tangentialrela tion to a circle of rotation of the latter, a spherically curvedsurface of a given radius may be produced by a lap surface of lessradius, which is advantageous in that such a lap may be adjusted to andfrom radial and tangential position to compensate for wear of itsabrading surface. For instance, a lap having a conoidal abrading'surfacewhich is arcually curved respectively differently transversely andcircumferentially, when presenting a transverse line of contactto theglass in radial relation to the axis of rotation of the latter, producesa spherical surface of precisely the same radius as the transversecurvature of the lap surface, and, as the lap surface is rendered moreconvex by use, the line of contact may be shifted to tangential relationto a circle of rotation of the glass to produce a spherical surface ofthe given radius with the lap surface then of a less radius. Of course,such adjust ment to and from radial and tangential position is limitedto the extent of the radius of the circular perimeter of the minor lensareas.

My invention includes the various novel features of construction andarrangement of the conoidal laps hereinafter more definitely specified.

This is a division of my application Serial 12,028 filed March 4, 1915,wherein surfacing mechanism of the character herein described isclaimed. The method of surfacing herein described is claimed in myapplication Serial 30,716 filed May 27, 1915, which is also a division'of said application Serial 12,028.

In the drawings :Figure I is a fragmentary plan view of a surfacingmachine, "including vertically opposed spindles by which the glass andlaps may be respectively rotated; the upper spindle being capable ofaxial, oscillatory, and lateral adjustment. Said machine also includes alap supporting lever extending transversely to the axis of rotation ofthe glass, which is not only capable of universal oscillatory movementupon its fulcrum, to shift the laps to and from the glass, but is alsocapable of ad justment longitudinally with respect to its fulcrum, andby turning upon its longitudinal axis, to precisely determine thepositlon of the region of contact between the laps and glass, relativelyto the axis of rotation of the latter. One rotary conoidal lap isindicated in dash lines in position to present only a transverse line ofcontact of its annular abrading surface to the major lens surface of theglass, in tangential relation to a circle of rotation of said glass.

Fig. II is a vertical sectional view of a rotary glass holder and glass,and a rotary conoidal lap arranged to present only a transverse line ofcontact of its annular abrading surface to the minor lens surface ofsaid glass; said lap being supported by a coupiing connecting said upperspindle of the surfacing machine with a pivotal bearing for the lapspindle, which is capable of oscillatory adjustment in the plane of theline of contact of the lap with the glass; the lap spindle having meansresiliently engaging said bearing and'preventing axial displacement ofsaid lap.

Fig. III is a vertical sectional view similar to Fig. II but showing alap spindle bearing directly connected with the horizontal lever of.said sunfacing machine, without the interposition of the pivot hearingbar shown in Fig. II.

Fig. IV is a sectional view similar to Fig. II but showing a lap forabrading the major lens surfaces, provided with re taining means likethe lap shown in Fig. III.

Fig. V is a fragmentary sectional view of the lap shown in Fig. III,showing its abrading surface covered with a sheet of textile fabricsecured by an elastic sphincteral band.

Fig. VI is a diagrammatic plan view indicating, in dash lines, a laphaving its annular abrading surface presenting a transverse line ofcontact to said glass, at the minor lens area of the latter and inradial relation with the axis of rotation of the glass.

Fig. VII is a vertical sectional view showing laps adapted torespectively abrade the major. and minor lens surfaces, mounted upon acommon spindle, upon which they may be independently rotated atdifferent speeds.

Fig. VIII is a fragmentary sectional 7 view of the laps shown in Fig.VII, with their abrading surfaces covered by respective sheets oftextile fabric secured by elastic sphincteral bands.

Fig. IX is a vertical sectional view, similar to Fig. VII, but showing asingle lap having the respectively differently curved annular abradingsurfaces for abrading the major and minor lens surfaces. 7

Fig. X is a plan view similar to Fig. VI but showing that the contactbetween the lap and the glass arranged as in Fig. IX is only at a line,which is radial with respect to the lap axis, because both of theannular surfaces of said lap are respectively diflerently curvedtransversely and circumferentially.

Fig. XI is a vertical sectional view similar to Fig. IX but showing alap having an annular abrading surface for the major lens surfaces whichis spherically curved 2'. 6., arcually curved the same both transverselyand circumferentially, whereas, the annular abrading surface for theminor lens surfaces is arcually curved respectively differentlytransversely and circumferentially.

Fig. XII is a plan view similar to Fig. X but showing that whereas theannular abrading surface of the lap shown in Fig. XI for abrading theminor lens surfaces presents only a line of contact to the glass, whichis radial with respect tothe lap axis; the annular abrading surface ofsaid lap for the major lens surfaces presents an area of contact to theglass which is a lune of a spherical surface.

Fig. XIII is an elevation, partlyin longitudinal section, of thesurfacing machine, shown in Fig. I, looking toward the left in thatfigure, but with the upper and lower spindles in the positioncontemplated in Fig. II and showing the lever support and its a'apurtenances as in Fig. IX.

Fig. XIV is an elevation, partly in trans verse section, of thesurfacing machine shown in Figs. I and XIII.

The machine shown in Fig. I may be conveniently employed in roughingglass blanks, by rotating them and a lap upon a common axis butrespectively different spindles which are relatively adjustable bothaxially and laterally and, preferably, rotated in opposite directions soas to attain the maximum speed of grinding with the minimum centrifugaldischarge of the abrading material. In said machine, the lower spindle 8is journaled in the base frame 1 and has the pulley 9 for rotation bythe belt 10, and has the conical cap 11 for detachable engagement withthe glass holder 12 upon which'the lens blanks 13 are detachablymounted, conveniently with pitch cement. Said base 1 also supports thetable 15 upon which the pan 16 is removably supported in concentricrelation with said spindle 8. The upper spindle 18 which is journaled inthe frame 2, tiltable and capable of straight lateral movement on saidbase frame 1, is provided with the pulley 19 and belt 20 by which it maybe rotated. Said pulley 19 is keyed to said spindle 18 so that thelatter may be raised and lowered through it by means of the quill 22having rack teeth '23 engaging the gear 24 which may be turned by hand.

Said quill may be prevented from rotating by a suitable key, adjustableby the set screw 32. Said spindle 18 has at its lower end the conicalcap 29 for, detachable engagement, directly, with ordinary sphericallaps which may be rotated in axial alinement with, or eccentrically to,the spindle S, and glass holders 12 thereon, when the set screw 32 inthe quill is retracted. lVhen said spindle 18 is prevented from rotatingit may be used to support the other laps hereinafter described, forinstance as shown in Fig. 11, to precisely determine the approachthereof to the glass. However, it is to be understood that other meansmay be employed to effect the grinding of the blanks preliminary to theemployment of the laps which have their axes extending obliquely withrespect to the axis of rotation of the glass as herein set forth.

The lap supporting lever 34 shown in Figs. I and IX, and the lever 35shown in Fig. III, have a universal fulcrum support and stop mechanism,to precisely determine their positions, conveniently mounted upon saidtable 15 as shown in Fig. I. Said fulcrum support includes the socketbase in which the cylindrical shank 46 of the yoke 47 may be turned andvertically adjusted, and clamped by the set screw 48 when in adjustedposition said set screw 48 being in screw threaded engagement with saidbase 45. Said yoke 47 has the oppositely alined cone pointed screws 50engaging the sleeve 51 in which said levers may be turned andlongitudinally adjusted, and clamped in adjusted position by the setscrew 53 which is in screw threaded engagement with said sleeve.However, it may be observed that when said parts are adjusted andclamped by the screws 48 and 53, said levers are free to oscillate in avertical plane upon the common axis of said screws 50, and each lever isconveniently provided with a handle 55 by which it may be manipulated asa support by which the laps 56, 57 etc., may be presented in operativerelation with the pairs of lens blanks 13 supported and rotated by theholders 12 on the spindle cap 11.

Although when clamped by the screws 48 and 53, said levers 34 and 35 areostensibly prevented from moving except in a vertical plane; it ispractically impossible to make them so rigid that they can not beotherwise moved within the limit of their resilience, and, in fact, theymay be bent and twisted, without permanent distortion, when clamped bythe supporting means above described, to such a degree that I find itconvenient to provide stop mechanism for the handle end of said leversby which their movement may be precisely limited. As shown in Fig. I;the stop bracket 60, mounted upon said table 15, carries the stop block61 upon the bolt 62 which has a squared shank mounted to slide in theslot 63 in said bracket and is provided with the wing nut 64 by whichsaid block 61 may be secured in any position of adjustment to which itmay be shifted by the thumb screws 65 and 66 which are in screw threadedengagement with said bracket 60. Each lever is conveniently providedwith a stud 68 which may be selectively engaged with any link of thechain 69 at the upper end of the spring 70 which is connected with saidbracket 60, at its lower end, by the screw 71, and it is to beunderstood that the approach of the laps to the glass, both laterallyand vertically, is precisely predetermined and limited by the locationof said stop block 61. For instance, said levers may be set to present alap in position to abrade the glass carried by the holder 12 and with aspace between the lower side of said lever and the proximate uppersurface of the recessed end of said block 61 corresponding with thethickness of the glass which is to be removed, and, said spring 70 beingconnected with said lever 52 as above described, the abrading operationmay proceed without further attention of the operator except as to themaintenance of the proper quantity of abrading material and water orother liquid vehicle between the lap and the glass.

It is to be understood that although I have shown the glass upon theholders 12 in the form of individual lens blanks 13, other forms may beemployed with equal 100 facility, for instance, a single piece of glassof the outer configuration of the holder 12, may be suitably surfacedand subsequently cut apart, at its shortest diameter, to form a pair ofbifocal lenses, or a circular glass 1 5 blank may be thus surfaced andsubsequently cut apart, upon any diametrical line to form a pair ofbifocal lenses.

Fig. II is a vertical sectional view showing the lap spindle bearingcasing 75 supported by a detachable coupling 76 connecting it with thecap 29 of the upper spindle 18 of the machine shown in Fig. I; saidspindle 18 being rigidly connected with the vertically adjustable quill22 when thus 11 used. Said coupling 76 has the set screw 7 7 forsecuring it in adjusted position upon said cap 29, so that said couplingmaybe turned to present the axis of the lap spindle in a plane which isradial to the.axis of rotation of the glass holder 12 or in tangentialrelation to a circle of rotation of the glass as above contemplated.Said coupling 76 also has the set screw 78 by which the pivot bar 80 maybe rigidly held in adjusted position; said bar being bifurcated at itslower end to receive the radial flange 81 of said spindle bearing casing75, which is pivotally connected therewith by the screw 83 which has asmooth cylindrical portion extending through said flange 81 but is inscrew threaded engagement with said bar 80. The oscillatory movement ofsaid flange 81 in said bar 80 is limited and the parts clamped inadjusted relation by the screw 85 which extends freely through theopenings 86 in said bar but is in threaded engagement with said flange81. Said screw may be jammed in adjusted position by the nut 87.

Said lap spindle bearing casing carries a ball bearing including theouter shell 89 tightly fitted in said casing 75 and the sleeve 90rotatable in said casing, and the lap 57, has its spindle 91 providedwith means for preventing accidental axial displacement of the lap,including the resilient ring 92 which is normally of slightly largerdiameter than said spindle but is compresset to frictionally engage saidsleeve 90, as shown in Fig. II, when said spindle is thrust through saidsleeve 90 into the operative position shown in said figure.

Said lap 57 is adapted to abrade the minor lens surfaces 99 on adiametrical line, as indicated at 107 in Fig. VI;'said line extending ina radial plane with respect to the axis of rotation of said lap 57 andtrans versely to the annular conoidal abrading surface thereof.

Fig. III is a vertical sectional view similar to Fig. II, but showing alap spindle bearing casing 109 directly connected with and supported bythe horizontal lever 35, with which it may be rig-idly connected by theset screw 111. Said lever 85 be conveniently supported, adjusted and setin connection with said surfacing machine, like the lever 3% abovedescribed. Said casing 109 inclo ses a ball bearing similar to thatshown in Fig. II, including a sleeve 90 having an annular recess whichis adapted to detachably engage the spring 11st which is seated in theslot 115 of the spindle 116 of the lap 117. Said spring has its upperend rigidly connected with said spindle 115 but is free to'resilientlyoscillate radially with respect to said spindle and normally projectstherefrom to the extent indicated in Fig. IV. Said bearing casing 109 isconveniently provided with the screw cap plate 118 at its lower end toretain the felt washer 119, through which said spindle is inserted andremoved, so as to automatically wipe and oil said spindle each time itis inserted. Said lap 117 is otherwise constructed like the lap 57 andsimilarly adapted to abrade the minor lens surfaces 99 on a diametricalline as indicated at 107 in Fig. VI.

Fig. IV shows the lap 56 (which is indicated by dash lines in Fig. I),having its spindle 112 provided with a spring 114: like the lap 117 butbeing otherwise constructed like the lap 51' above described and adaptedto abrade the major lens surfaces 98 on the line 120 tangential to acircle of rotation of the glass, as indicated in Figs. I and VI; saidline extending in a radial plane with respect to the axis of rotation ofsaid lap 56 and transversely to the annular conoidal abrading surfacethereof. As above set forth, said lap may be thus disposed with its axisin tangential relation to a circle of rotation ofthe glass, not only toimpart the maximum scribbling motion to the abrading material, but toform a spherical lens surface of a given radius, with the abradingsurface of the lap having a transverse curvature of less radius.

In the position shown. in Figs. I and IV, said lap 56 is so set that thesmaller circumferential edge of its abrading surface, which is incontact with the glass 18, is tangential to the circular junction linebetween the major lens areas 98 and the minor lens areas 99. Saidjunction line is indicated in Figs. II, III, IV, and in other sec tionalviews of the glass, by short straight lines which extend verticallydownwardly from the upper surface of the glass, but which are notintended to indicate any division in the glass, but merely to indicatethe position of the laps with reference to said junction lines which areotherwise ditlicult to locate in the sectional views'in view of theslight difference in curvature between the adjoining surfaces. It may beobserved, with reference to Fig. IV, that said smaller circumferentialedge of the abrading surface of the lap 56 extends obliquely over saidjunction line from its point of contact with the glass; whereby theglass is abraded by said lap in adirection transverse to said junctionline, so as to sharply define the latter; the glass being rotated in thedirection of the arrow in Fig. I while the lap is rotated in the samedirection. Although said lap may be caused to rotate in that directionmerely by frictional engagement with the surface ofthe glass rotating inthat direction, I find it preferable to rotate all of the laps at ahigher speed than the glass and this may be conveniently done by thebelt 121 engaging the respective grooves 122 in the lap, as shown inFigs. II, III and IV, and extending thence around any suitable drivingpulley. The reason for rotating the glass, is, of course, tosuccessively present at the line of contact with the laps all of thearea of the glass which is to be abraded by the latter. The reason forrotating the laps at a higher speed is to attain the maximum relativemovement of the lap and glass surfaces which is possible with theemployment of a pulverulent abrading medium; such speed being limited bythe centrifugal effect upon said material, for, ifthe laps are rotatedat too great a'speed said material will'be thrown off the glass uponwhich it must be retained tohave any abrading effect. The reason forrotating the laps in the same direction as the glass is to minimize thechance of producing scratches by irregular particles of the abradingmaterial which might be retained in damaging relation to the glass ifthe glass and laps are rotated in opposite directions, as the abradingmaterial is then piled up by the opposite feeding movement thereof bythe glass and laps.

Of course, said lever 34, is set in respectively different positions inorder to present the annular abrading surfaces of said laps 56, 57 etc.,respectively in operative relation with the major and minor lenssurfaces of the glass 13. The position of said lever shown in full linesin Fig. I is ap proximately that which it occupies when supporting saidlap 56 as shown in Figs. I, and IV. The dash line which is radial to thecenter of oscillation of said lever 34 in Fig. I indicates its positionwhen supporting the lap 57 as in Fig. II, it being thus shifted slightlymore to the right, to bring the smaller circumferential line of itsannual abrading surface tangential to the circle defining the minor lensareas in Figs. I and VI; and as indicated by the smaller elliptical dashline in Fig. VI.

It is to be understood that any of said laps may be provided with acover of textile fabric or other flexible sheet material 125 retainedthereon by an elastic sphincteral band 126 as shown in Figs. II and V;such coverings serving as vehicles to retain the pulverulent abradingmaterial upon the abrading surfaces of the laps.

Although I find it convenient to employ the respectively independentlaps above described so that the minor and major lens surfaces may beabraded by different operators at different times; it is to beunderstood that such conoidal laps may be employed to simultaneouslyabrade both the major and minor surfaces of the same glass. Forinstance, as shown in Fig. VII, the laps 128 and 129 which have annularabrading surfaces respectively adapted to abrade. the major lenssurfaces 98 and minor lens surfaces 99 of the glass 13 which is rotatedby the holder 12, shown in said figure, have the common spindle 130 andmay be simultaneously rotated, upon the same axis, by the belts 121, atrespectively different speeds, if desired, or they may both be rigidlyconnected with said spindle by their respective set screws 131 and 132so as to be rotated to gether. The relative axial position of said laps128 and 129 may be precisely predetermined by adjustment of the nuts 134which are in screw threaded engagement with the inner hub of said lap128. Such construction and arrangement is advantageous in that the laps128 and 129 may have their abrading surfaces separately ground to avariable extent and yet be precisely adjusted for the desiredcoiiperative effect upon the glass.

Whether rotated independently or clamped together, as above described;said laps 128 and 129 are conveniently mounted for rotation in thespindle bearing pivot frame 136 having the adjustable bearing screws 137and 138 which may be set to hold said spindle 130, or the spindles ofany of the laps above described. Said pivot frame 136 is convenientlymounted for oscillation in the yoke 139 which has the set screw 140 forsecuring it in rigid relation with the cap 29 of the spindle 18 abovedescribed, and carries at the lower ends of its bifurcations, opposite,axially alined screws 142 having conical heads 143 fitted incorresponding sockets in said pivot frame 136 and having wing nuts 144,exterior to said yoke 139 so that said frame 136 may be freed foroscillation in said yoke or clamped in rigid relation therewith. Iprefer to limit the oscillatory movement of said frame 136 in said yoke139 by providing the latter with the clamping screw 147 having theconical head 148 extending in the arcual slot 149 in said frame 136;said screw 147 being provided with the wing nut 150 exterior to saidyoke, by which said frame 136 may be clamped in rigid relation with saidyoke. Of course, if a permanently rigid construction is desired, thebearing screws 137 and 138 may be directly mounted in the yoke 139,without the interposition of the 100 frame 136.

As indicated in Fig. VIII either or both .of said laps 128 and 129 mayhave its abrading surface provided with a cover of textile fabric orother flexible sheet material 125 retained thereon by an elasticsphincteral band 126.

As shown in Fig. IX, my improved surfacing mechanism may be furthersimplified by providing a single lap 153 having the respectivelydifferently curved annular abrading surfaces 154 and 155, meeting at thecircular line indicated at 156 and respectively adapted for abrading themajor lens surfaces 98 and miner lens surfaces 99 of the glass 13 whichis mounted to be rotated on i the holder 12 as above described. Said lap153 may be mounted for rotation in any of the lap spindle bearings abovedescribed but is siown mounted in the bearing 75 supported by the lever34 with which it is adjustably connected by the coupling 151 having theset screw 152 for securing the bar 80 of said bearing, and saidcoupling, in adjusted position on said lever.

Said lap 153 has annular abrading surfaces which are like those of thelaps 56, 57, etc., in that they are respectively differently arcuallycurved transversely and circumfere en'tially and, as indicated in Fig.X, the an- '130 nular abrading surfaces 154 and 155 of said 7 lap 153are in contact with the glass only at a line 158 which is radial withrespect to the lap axis.

As the laps above described present only respective lines of contact tothe major and minor lens surfaces, and the former are of greater areathan the latter, a longer time is required to produce a given surfaceupon the major areas than upon the minor areas, although the differenceis minimized by the relatively greater diameter and consequent surfacespeed of movement of the annular abrading surfaces of the laps which areapplied to the major areas. Therefore, I find it convenient to providethelap 160 shown in Fig. XI, which differs from the lap 153 abovedescribed inthat its annular abrading surface 161 which is presented tothe major glass surfaces 98 is spherically curved 6., arcually curvedthe same both transversely and circumferentially; so that, as indicatedin Fig. XII, said surface 161 presents an area of contact to the glasswhich is a lune of a spherical surface, the contour thereof, in plan,bein indicated by the dash lines 162 in Fig. 4 II. Said sphericalabrading surface'of the lap 160 terminatesat the circle indicated by thedotted line 16 in Fig. XI, and the adjacent annular abrading surface165, which is presented to the minor glass areas 99, is arciially curvedrespectively differently transversely and eir cumferentially so as topresent only a line of contact to the glass as indicated at 167 in Fig.XII. Such construction of the abrading' surface 165 isnecessitated bythe fact that its curvature (four dioptric) is of greater radiustransversely than thecurvature (six dioptric) of said abrading surface161, and, if said surface 165 were a zone of a sphere of such greaterradius it would, of course, sweep over the major glass areas 98 andeliminate the desired curvature of the latter. 7

It may be observed that in the employment of both of the laps 153 and160. the smaller circumferential edges of the abrading surfaces whichare respectively in contact with the major and minor glass areas extendobliquely over the circular junction line between said areas, fromrespectively opposite sides of said line whereby the glass is abraded'ina direction transverse to said junction line, so as to sharply define Itis'to be noted that the abrasion is not effected by the surface of thelap but by the pulv'erulent abrading'material which is free to movebetween the adjacent surfaces of the lap and glass, and has a motionwhich is the resultant not only of the circular rotation of the lap andglass with their axes in the oblique relation described, but of the socalled centrifugal force generated by such movement; the

verse to said junction line is clearly indicated by the score marksmadein the glass by granules of the abrading material. The expressionobliquely transverse is employed toindicate the contemplated directionmore precisely than is indicated by the word transverse alone, which iscompre hensive of the right angular relation as distinguished from thediagonal or oblique crossing movement contemplated, which is the resultof the traverse of the particles of the abrading material in evolutepaths, under the several forces acting upon them as aforesaid. 7

It is to' be understood that said laps 153 and. 160 may have theirabradingsurfaces covered with textile fabric or other flexible sheetmaterial 125 retained thereon by elastic s hincteral bands 126, asindicated in Fig. I.

It may be observed that the ball bearings above described have no meansfor compensating for wear which is incident to the rotation of the lapsat high speed, and, although they are of an ordinary commer cial typeand may be readily and cheaply replaced, I prefer to employ in each ofthe lap spindle bearings above described, ball bearings which areadjustable to not only i -in their respective diameters. Said sleeve 172has its conical end 173 encircled by the double conical annular ballrace ring 175 for the balls 176 which are embraced tween said ring 175and the nut 178 which is in screw threaded engagement with the upper endof said slee've 172. Said nut 178 is a complete annulus but has radialnotches 17 9 which may be engaged by a screw driver or similar implementinserted through the opening 180 in saidbearing casing 170 to hold saidnut 178 temporarily stationary while the sleeve 172 is being adjusted inengagement therewith. The construction and arrangement above describedis such that when said nut 17 8jis temporarily prevented from rotatingwith the sleeve 172,

and the latter is turned, either by a tool en aging the radial slotstherein or by frictional engagement with the lap spindle, said nut 178is drawn toward the race ring 17 5 to take up all lost motion. Saidscrew thread connecting said sleeve 172 with said nut 178 is preferablyso inclined as to be tightened by rotation of said sleeve in thedirection in which itis rotated with the lap spindle.

Although the supports for the lap spindle bearings above described ascapable of oscillatory movement may be rigidly secured when adjusted tothe proper angle to produce the desired surface upon the glass, and thecurvature of the glass surfaces abraded by the laps thus supported maybe precisely predetermined by such adjustment and maintenance of thelaps; it is to be noted that ordinarily lens surfacing operations arefacilitated by permitting the laps to have such freedom of movement asto accommodate themselves to the curvature of the glass, particularlyduring the polishing operation. Therefore, it may be observed that thebearings constructed and arranged in accordance with my invention asabove described, permit such freedom of movement, and laps embodying myinvention may be thus used. For instance, glass which has been surfacedto the desired curvature by any convenient means and requires to befinally finished or polished may be sub jected to the operation of theconoidal laps above described, with the latter free to oscillate to suchextent as to accommodate themselves to the curvature determined by theglass itself, and, in such use of said laps their effect is rendered asaccurate as possible by the fact that their centers of oscillation arenearer the surface of the glass being abraded than the center ofcurvature of the surface which is being formed; so as to stabilize thelaps, with respect to the glass, regardless of their freedom aforesaid.It may be observed that in Fig. VII the center of oscillation of thelaps is below the surface of the glass which is being abraded, asdistinguished from the construction and arrangement illustrated in thepreceding figures, wherein the centers of oscillation of the respectivelaps are above the glass; however, in either case, the centers ofoscillation are intermediate of the length of the lines of contact ofthe laps with the glass. Moreover, it is to be noted that when permittedsuch freedom of oscillation, it is limited to planes which are radialwith respect to the laps and coincident with the lines of contact whichthe laps present to the glass.

It is to be noted that all chords of the transverse curves of the doublezoned surfacing tools above described converge toward their axes, in thesame general direction; whereby all abrading surfaces of each such toolare adapted to receive a covering of said textile fabric or otherflexible sheet material 125, which is, of course, primarily plane. Ifthe chords of'said abrading sur faces were parallel, or approximatelyparallel, with the axes of rotation thereof; it would be impossible tothus provide said surfaces with a seamless textile covering of saidprimarily plane sheet material. i' It is practically impossible toemploy a seamed covering because of the incident irregularities in thesurface thereof which produce defects in the glass surface.

I do not desire to limit myself to the precise details of constructionand arrangement above described as it is obvious that variousmodifications may be made therein without departing from the essentialfeatures of my invention as defined in the appended claims.

I claim 1. A rotary lap having a perimetral abrading surface extendingtransversely to its axis of rotation and arcually curved respectivelydifferently concentrically to said axis and transversely thereto; oneedge of said surface being nearer the lap axis than the opposite edge.

2. In surfacing mechanism, the combination with a rotary lap having anannular abrading surface and an axial spindle in rigid relationtherewith, and a conical bearing surface at each end of said spindle; ofa support movable toward and away from the material to be surfaced; andmeans detachably connecting said lap with said support, including apivoted member having axially adjustable conical bearing surfacesarranged to detachably engage the ends of said spindle.

3. 1n surfacing mechanism, the combination; with a rotary lap'having anannular abrading surface and an axial spindle in rigid relationtherewith, and a conical bearing surface at each end of said spindle; ofa support movable toward and away from the material to be surfaced; andmeans detachably connecting said lap with said support, including amember having axially adjustable conical bearing surfaces arranged toetachably engage the ends of said spindle.

l. In surfacing mechanism, the combination with a rotary lap having atransversely curved abrading surface and an axial spindle extendingobliquely to said surface in rigid relation therewith, and a conicalhearing surface at the end of said spindle; of a support movable towardand awayfrom the material to be surfaced; and means detachablyconnecting said lap with said support, including a member having arraxially adjustable conical bearing surface arranged to detachably engagethe end of said spindle.

5. A rotary lap having a rigid spindle, an

' ing an annular conoidal abrading surface annular abrading surfacewhich is aspherical zone, in concentric relation with said spindle, andan annular abrading surface, in concentric relation with said spindle,curved respectively differently transversely and circumferentially; thechords of the transverse arcs of each of said surfaces beinginclinedwith respect to the axis of said spindle.

V 6. A rotary surfacing tool having, in concentric relation to a commonaxis, two distinct and differently curved annular abrading zones, invariable axially spaced relation; one being curved respectivelydifferently transversely and circumferentially; the greatest radialextent of each of said zones, from said axis, being less than the radiusof curvature of its abrading surface; all chords of transverse curves ofsaid zones converging toward said axis, in the same general direction.

7. A rotary surfacing tool having, in concentric relation to a commonaxis, two distinct and differently curved annular abrading zones; onebeing curved respectively differently transversely andcircumferentially; the greatest radial extent of each of said zones,from said. axis, being less than the radius of curvature of lts abradingsurface;

all chords of transverse curves of said zones converging toward saidaxis, in the same general direction. 7

8. A rotary surfacing tool having, in concentric relation to a commonaxis, two distinct and differently curved annular abrading zones; onebeing curved respectively differently transversely andcircumferentially; all chords of transverse curves of said zonesconverging toward said axis, in the same general direction.

9. A rotary surfacing tool having, in concentric relation to its axis,an annular abrading zone, curved respectively differently transverselyand circumferentially; the greatest radial extent of said zone, fromsaid axis,.being less than the radius of transverse curvature of itsabrading surface; all

chords of transverse curves of said zone converging toward said axis.

10. A rotary surfacing tool having two distinct annular abrading zonesconcentric with its axis; one being a zone of a sphere, and the otherbeing curved respectively differently transversely andcircumferentially; the greatest radial extent of each of said zones,from said axis, being less than the radius of. said sphere.

'11. In bifocal lens surfacing mechanism, the combination with a rotaryholder for the glass which is to be abraded; of two rotary laps havingacommon axis, and each havarcually curved differently circumferen tiallyand radially; said abrading surfaces being curved differently in therespective laps; means arranged to present said laps with said abradingsurfaces in respective operative relation to the respective lens areas,with only a'transverse line of contact between each lap and the lensarea which it is to abrade, in a plane which is radial to the axis ofrotation of the respective lap, and with .their smaller circumferentialedges tangential to the junction line between said lens areas, so thatsaid edges extend over said line from the respective, points of contactof said laps with the surfaces to be abraded, and from respectivelyopposite sides of said line; whereby the edges of the respective lensareas adjoining said line are abraded transversely to said line, so asto sharply define the latter: means supporting said laps. permittingoscillation of their respective axes; means limiting such freedom ofoscillation ofeach lap to a plane which is radial to its axis; meansarranged to positively rotate said holder; and means arran ed topositively rotate the respective laps, independently of each other.

' 12. In bifocal lens surfacing mechanism, the combination with a rotaryholder for the glass which is to be abraded; of two rotary laps, eachhaving an annular abrading surface arcually curved differentlycircumferentially and radially; means arranged to present said laps withsaid abrading sur faces in respective operative relation to therespective lens areas, with only a transverse line of contact betweeneach lap and the lens area which it is to abrade, and with their smallercircumferential edges at the junction line between said lens areas, sothat said edges extend over said line from the respective pointsofcontact of said laps with the surfaces to be abraded, and fromrespectively opposite sides of said line; whereby the edges of therespectivelens areas adjoining said line are abraded transversely tosaid line, so as to sharply define the latter means supporting saidlaps, permitting oscillation of their respective axes; means limitingsuch freedom of oscillation of each lap to a plane which is radial toits axis; means arranged to positively rotate said holder; and meansarranged to positively rotate the respective laps, independently of eachother.

13. In bifocal lens surfacing mechanism, the combination with a rotaryholder for the glass which is to be abraded; of two rotary laps, eachhaving an annular conoidal abrading surface arcually curvedcircumferentially and radially; means ar-,

ranged to present said laps with said abrading surfaces in respectiveoperative relation to the respective lens areas, with only a transverseline of-contact between each lap and the lens area which it is toabrade, and

with one circumferential edge of each lap at the unction line betweensaid lens areas,

so that said edges extend over said line from the respective points ofcontact of said laps with the surfaces to be abraded, and fromrespectively opposite sides of said line; whereby the edges of therespective lens areas adjoining said line are abraded transversely tosaid line, so as to sharply define the latter; means supporting saidlaps, permitting oscillation of their respective axes; means limitingsuch freedom of oscillation of each lap to a plane which is radial toits axis; means arranged to positively rotate said holder; and meansarranged to positively rotate the respective laps, independently of eachother.

let. In bifocal lens surfacing mechanism, the combination with a rotaryholder for the glass which is to be abraded; of two rotary laps, havinga common axis, and each having an annular conoidal abrading surfacearcually curved differently circumferentially and radially; saidabradingsurfaces being curved differently in the respective laps; means arrangedto present said laps with said abrading surfaces in respective operativerelation to the respective lens areas, with only a transverse line ofcontact between each lap and the lens area which it is to abrade, in aplane which is radial to the axis of rotation of the respective lap, andwith their smaller circumferential edges tangential to the junction linebetween said lens areas, so that said edges extend over said line fromthe respective points of contact of said laps with the surfaces to beabraded, and from respectively opposite sides of said line; whereby theedges of the respective lens areas adjoining said line are abradedtransversely to said line, so as to sharply define the latter.

15. In bifocal lens surfacing mechanism, the combination with a rotaryholder for the glass which is to be abraded; of two rotary laps, eachhaving an annular abrading surface arcually curved differentlycircumferentially and radially; means arranged to present said laps withsaid abrading surfaces in respective operative relation to therespective lens areas, with only a transverse line of contact betweeneach lap and the lens area which it is to abrade, and with their smallercircumferential edges at the junction line between said lens areas, sothat said edges extend over said line from the respective points ofcontact of said laps with the surfaces to be abraded, and fromrespectively opposite sides of said line; whereby the edges of therespective lens areas adjoining said line are abraded transversely tosaid line, so as to sharply define the latter.

16. In bifocal lens surfacing mechanism, the combination with a rotaryholder for the glass which is to be abraded; of two rotary laps, eachhaving an annular conoidal abrading surface arcually curvedcircumferentially and radially; means arranged to present said laps withsaid abrading surfaces in respective operative relation to therespective lens areas, with only a transverse line of contact betweeneach lap and the lens area which it is to abrade, and with onecircumferential edge of each lap at the junction line between said lensareas, so that said edges extend over said line from the respectivepoints of contact of said laps with the surfaces to be abraded, and fromrespectively opposite sides of said line; whereby the edges of therespective lens areas adjoining said line are abraded transversely tosaid line, so as to sharply define the latter.

In testimony whereof, .I have hereunto signed my name at Philadelphia,Pennsylvania, this fourth day of June, 1915.

ARTHUR E. PAIGE.

Witnesses:

FRANK E. PAIGE, ANNA IsRmLvrrz.

